A few times I have tried to find the name of a library containing a particular class name. It is not something one needs often, but for those rare occasions I have not found a consistent way for such a search.
That shouldn't be too much work to do, I thought, and I haven't had a hobby project for a while. Two weekends and 50 GB of data later I'm launching a maven search site:
http://jaclaz.com/jacla/search.do
As an extra, all javadocs and sources can be browsed online if present in the repository.
PS: I underestimated how complex it is t keep a PC on 24/7 at home. The site is off-line.
PPS: On-line as http://alljavaclasses.com
